One of my favorite set/rep schemes is one I call challenge sets. Here's what challenge sets would look like on hack squats:

I typically do multiple sets working my way up in weight. In the video, I'm using both bands and chains to deload weight at the bottom of the movement, but that's not necessary.

The key is to work up to a tough working weight whereby you'd do 4 sets of 6-8 reps. However, rather than doing all 4 working sets, only do 3. The first two are standard 6-8 rep sets, but the third is a challenge set where you'd do as many reps as possible.

I like these for a couple reasons: First, they shock the body by pushing you beyond mental limits, and you MUST push yourself. Second, when you throw out a predetermined rep number you typically far exceed what you thought possible going into the set. I think I got 16 reps in the video with a weight normally used for 6-8. Knowing you have fewer total sets to do, and that the challenge set is a single balls-out-effort, frees you up to not hold back.

I'd only select one exercise per body part per workout for this. Basically, sprinkle them into your training sparingly or you'll risk burning out your CNS.